HID: hid-input: allow input_configured callback return errors

When configuring input device via input_configured callback we may
encounter errors (for example input_mt_init_slots() may fail). Instead
of continuing with half-initialized input device let's allow driver
indicate failures.

Signed-off-by: Jaikumar Ganesh <jaikumarg@android.com>
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Nikolai Kondrashov <Nikolai.Kondrashov@redhat.com>
Acked-by: Andrew Duggan <aduggan@synaptics.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>